Single, dual and quad channel memory performance: More lanes, more speed?

New insights in the role of multichannel memory



These days a decent PC will support dual channel memory, while high-end desktops usually go with quad channel memory. Does this actually improve performance, and if so, how much and for which applications? We researched it for you.

A frequent Hardware.Info reader who builds their own system, will generally fill up at least two memory slots. This is because the effective bandwidth increases when multiple memory channels are in use. However, if you purchase a prebuilt system in a shop, or if you buy a laptop from the cheaper segment, you will quite often find that only a single memory channel is used. If you're lucky, you might be able to fill up the second slot yourself and upgrade the capacity this way. We were wondering whether the usage of multiple memory channels actually improves performance.

It's useful to know whether you sacrifice performance when opting for a single memory module, especially if you don't have the option to upgrade afterwards. Furthermore when you're purchasing a system with only two memory slots, you'll be able to more easily decide whether you'll fill up both slots or leave one empty and equip the other one with a higher capacity. This is mainly important for mini-ITX systems. To find out whether the extra bandwidth actually has an impact, and if so, how much, we performed a large number of tests with two test platforms.

More lanes

By driving memory parallelly, with two or four channels (called dual, respectively quad channel) you can double, or quadruple, the effective bandwidth of the memory in your system. For clarification purposes: bandwidth is not the same as speed. The speed (the amount of MHz) of the memory determines how often data can be transported. That frequency does not increase with dual or quad channel, however what does happen, is that every time respectively two to four times more data can be sent compared to normal. You can compare it to a highway that doesn't have a higher speed limit, but more lanes.

The main advantage to using multiple channels is the 'free' performance increase: the only thing you have to do is purchase multiple memory modules, instead of a single one. The timings (latency) also do not increase, whereas they the timings of faster memory are generally higher compared to those slower memory.

The speed of the memory has not been the bottleneck for most applications for a long time now, however there are a couple of programs here and there that do benefit significantly from it. You also get performance increases in places where you would not expect them at all. According to one of our recent tests faster memory can lead to better performance in games, under certain circumstances, which is something we have not seen in a long time.

Considering the difference between bandwidth and speed we can't automatically conclude that larger bandwidth will have the same positive effects. In this review we take a look at the performance differences between dual and quad channel memory compared to single channel memory. Perhaps larger bandwidth will give us the same performance increases as faster memory.

Also read these memory module articles on Hardware.Info

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